Liquid crystal display device

ABSTRACT

A liquid crystal display device is provided which can enhance a numerical aperture. The display has a pixel transparent conductive film electrode and a transparent conductive film counter electrode formed on an insulation film, which in turn is formed on a first substrate to cover the pixel electrode. A plurality of linear portions of the counter electrode are arranged on the pixel electrode. A gate-signal-line side of the pixel electrode of the first pixel is formed on a first-pixel side of the gate signal line and a gate-signal-line side of the pixel electrode of the second pixel is formed on a second-pixel side of the gate signal line. The gate-signal-line-side frame portion of the counter electrode of the first pixel and the gate-signal-line-side frame portion of the counter electrode of the second pixel are formed in common on the gate signal line in a striding manner.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of U.S. application Ser. No.12/379,405 filed on Feb. 20, 2009. Priority is claimed based on U.S.application Ser. No. 12/379,405 filed on Feb. 20, 2009, which claimspriority from Japanese application JP 2008-070579 filed on Mar. 19,2008, which is hereby incorporated by reference into this application.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a liquid crystal display device, andmore particular to an IPS (In Plane Switching)-method liquid crystaldisplay device.

2. Background Art

As such a liquid crystal display device, there has been known a liquidcrystal display device having the following constitution. Out of a pairof substrates which are arranged to face each other with liquid crystalsandwiched therebetween, in a pixel region formed on aliquid-crystal-side surface of one substrate, a first electrode having aplanar shape formed of a transparent conductive film and linear secondelectrodes formed of a plurality of transparent conductive films areformed. Here, the first electrode is formed on the whole pixel region,and the linear second electrodes are formed in parallel to each other onan upper surface of an insulation film which is formed so as to alsocover the first electrode in a state that the linear second electrodesoverlap with the first electrode.

Molecules of the liquid crystal are driven by an electric fieldcontaining components parallel to the substrate between the firstelectrode and the second electrode and hence, the IPS-method liquidcrystal display device is excellent in a so-called wide viewing angle.Further, both of these electrodes are formed of a transparent conductivefilm and hence, the IPS-method liquid crystal display device alsoexhibits an excellent numerical aperture.

Such a liquid crystal display device is usually driven by a so-calledactive matrix method in general. That is, the liquid crystal displaydevice defines a region surrounded by a pair of neighboring gate signallines and a pair of neighboring drain signal lines as a pixel region,and includes, in the pixel region, a thin film transistor which isturned on in response to a signal from the gate signal line, a pixelelectrode to which a signal from the drain signal line is supplied viathe turned-on thin film transistor, and a counter electrode whichgenerates an electric field for driving liquid crystal between the pixelelectrode and the counter electrode.

With respect to a liquid crystal display device having suchconstitution, there has been known a liquid crystal display device inwhich the first electrode functions as the pixel electrode and thesecond electrode functions as the counter electrode or a liquid crystaldisplay device in which the first electrode functions as the counterelectrode and the second electrode functions as the pixel electrode.

Such a liquid crystal display device is disclosed in WO01/018597 (patentdocument 1), for example.

SUMMARY OF THE INVENTION

However, in the above-mentioned liquid crystal display device, it isnecessary to supply a video signal to the pixel electrode independentlyfor every pixel and hence, the pixel electrode of the pixel and thepixel electrode of another pixel which is arranged adjacent to the pixelare formed in a pattern which are separated from each other physicallyas well as electrically.

However, the pixel electrode is arranged such that a gap is formedbetween the pixel electrode and the gate signal line or the drain signalline which defines the pixel (in a state that the pixel electrode doesnot overlap with the gate signal line or the drain signal line).Accordingly, when a signal is supplied to the gate signal line, forexample, lines of electric force which start from the gate signal lineterminate at the respective pixel electrodes on both sides of the gatesignal line.

These lines of electric force generate an electric field which becomes acause of so-called leaking of light around the gate signal line andhence, a black matrix (light blocking film) which sufficiently coversthe gate signal line is formed on a substrate opposite to the gatesignal line by way of liquid crystal.

In this case, a width of the black matrix becomes larger than a width ofthe gate signal line and hence, the enhancement of a numerical apertureof the pixel is impeded, and there has been a demand for overcoming sucha drawback.

Accordingly, it is an object of the present invention to provide aliquid crystal display device which can increase a numerical aperture.

To briefly explain typical inventions among inventions described in thisapplication, they are as follows.

(1) The present invention is directed to a liquid crystal display devicehaving a first substrate and a second substrate which are arranged toface each other with liquid crystal sandwiched therebetween, wherein thefirst substrate forms a plurality of gate signal lines and a pluralityof drain signal lines on a liquid-crystal-side surface thereof, assuminga region surrounded by a pair of neighboring gate signal lines and apair of neighboring drain signal lines as a pixel region of one pixel,the pixel includes a thin film transistor which is turned on in responseto a signal from the gate signal line, a pixel electrode to which asignal from the drain signal line is supplied via the thin filmtransistor, and a counter electrode which generates an electric fieldfor driving the liquid crystal between the pixel electrode and thecounter electrode which are formed on the liquid-crystal-side surface ofthe first substrate, the pixel electrode is formed of a transparentconductive film having a planar shape which is formed in each pixelregion on a first insulation film which is formed on the first substrateso as to cover the gate signal line, the counter electrode isconstituted of a transparent conductive film which includes a pluralityof linear portions arranged parallel to each other and a frame portionwhich connects end portions of the linear portions to each other, thetransparent conductive film of the counter electrode being formed on asecond insulation film which is formed on the first substrate so as tocover the pixel electrode, and the plurality of linear portions of thecounter electrode being arranged on the pixel electrode in anoverlapping manner, and assuming two pixels which are arranged adjacentto each other with the gate signal line formed as a boundarytherebetween as a first pixel and a second pixel respectively, agate-signal-line side of the pixel electrode of the first pixel isformed on a first-pixel side of the gate signal line in an overlappingmanner, and a gate-signal-line side of the pixel electrode of the secondpixel is formed on a second-pixel side of the gate signal line in anoverlapping manner, and the gate-signal-line-side frame portion of thecounter electrode of the first pixel and the gate-signal-line-side frameportion of the counter electrode of the second pixel are formed incommon on the gate signal line in a striding manner.

(2) In the liquid crystal display device having the constitution (1),the liquid crystal display device forms alight blocking film which isarranged so as to overlap with the gate signal line on the secondsubstrate, and a width of the light blocking film is set smaller than awidth of the gate signal line.

(3) In the liquid crystal display device having the constitution (1),assuming two pixels which are arranged adjacent to each other with thedrain signal line formed as a boundary therebetween as one pixel andanother pixel respectively, a drain-signal-line side of the pixelelectrode of said one pixel is formed on one-pixel side of the drainsignal line in an overlapping manner, and a drain-signal-line side ofthe pixel electrode of said another pixel is formed on another-pixelside of the drain signal line in an overlapping manner, and thedrain-signal-line-side frame portion of the counter electrode of saidone pixel and the drain-signal-line-side frame portion of the counterelectrode of said another pixel are formed in common on the drain signalline in a striding manner.

(4) The present invention is also directed to a liquid crystal displaydevice having a first substrate and a second substrate which arearranged to face each other with liquid crystal sandwiched therebetween,wherein the first substrate forms a plurality of gate signal lines and aplurality of drain signal lines on a liquid-crystal-side surfacethereof, assuming a region surrounded by a pair of neighboring gatesignal lines and a pair of neighboring drain signal lines as a pixelregion of one pixel, the pixel includes a thin film transistor which isturned on in response to a signal from the gate signal line, a pixelelectrode to which a signal from the drain signal line is supplied viathe thin film transistor, and a counter electrode which generates anelectric field for driving the liquid crystal between the pixelelectrode and the counter electrode which are formed on theliquid-crystal-side surface of the first substrate, the counterelectrode is formed of a transparent conductive film having a planarshape which is formed in a state that the transparent conductive film ofthe counter electrode extends over the neighboring pixel striding overat least the gate signal line, the transparent conductive film of thecounter electrode being formed on a first insulation film which isformed on the first substrate so as to cover the gate signal line, thepixel electrode is formed of a transparent conductive film whichincludes a plurality of linear portions arranged parallel to each otherand a frame portion which connects end portions of the linear portionsto each other, the transparent conductive film of the pixel electrodebeing formed in each pixel region on a second insulation film which isformed on the first substrate so as to cover the counter electrode, andthe plurality of linear portions of the pixel electrode being arrangedon the counter electrode in an overlapping manner, and assuming twopixels which are arranged adjacent to each other with the gate signalline formed as a boundary therebetween as a first pixel and a secondpixel respectively, a gate-signal-line-side frame portion of the pixelelectrode of the first pixel is formed on a first-pixel side of the gatesignal line in an overlapping manner, and a gate-signal-line-side frameportion of the pixel electrode of the second pixel is formed on asecond-pixel side of the gate signal line in an overlapping manner.

(5) In the liquid crystal display device having the constitution (4),the liquid crystal display device forms alight blocking film which isarranged so as to overlap with the gate signal line on the secondsubstrate, and a width of the light blocking film is set smaller than awidth of the gate signal line.

(6) In the liquid crystal display device having the constitution (4),assuming two pixels which are arranged adjacent to each other with thedrain signal line formed as a boundary therebetween as one pixel andanother pixel respectively, a drain-signal-line-side frame portion ofthe pixel electrode of said one pixel is formed on one-pixel side of thedrain signal line in an overlapping manner, and a drain-signal-line sideof the pixel electrode of said another pixel is formed on another-pixelside of the drain signal line in an overlapping manner.

(7) The present invention is also directed to a liquid crystal displaydevice having a first substrate and a second substrate which arearranged to face each other with liquid crystal sandwiched therebetween,wherein the first substrate forms a plurality of gate signal lines and aplurality of drain signal lines on a liquid-crystal-side surfacethereof, assuming a region surrounded by a pair of neighboring gatesignal lines and a pair of neighboring drain signal lines as a pixelregion of one pixel, the pixel includes a thin film transistor which isturned on in response to a signal from the gate signal line, a pixelelectrode to which a signal from the drain signal line is supplied viathe thin film transistor, and a counter electrode which generates anelectric field for driving the liquid crystal between the pixelelectrode and the counter electrode which are formed on theliquid-crystal-side surface of the first substrate, the pixel electrodeis formed of a transparent conductive film having a planar shape whichis formed in each pixel region on a first insulation film which isformed on the first substrate so as to cover the drain signal line, thecounter electrode is formed of a transparent conductive film whichincludes a plurality of linear portions arranged parallel to each otherand a frame portion which connects end portions of the linear portionsto each other, the transparent conductive film of the counter electrodebeing formed on a second insulation film which is formed on the firstsubstrate so as to cover the pixel electrode, and the plurality oflinear portions of the counter electrode being arranged on the pixelelectrode in an overlapping manner, and assuming two pixels which arearranged adjacent to each other with the drain signal line formed as aboundary therebetween as a first pixel and a second pixel respectively,a drain-signal-line side of the pixel electrode of the first pixel isformed on a first-pixel side of the drain signal line in an overlappingmanner, and a drain-signal-line side of the pixel electrode of thesecond pixel is formed on a second-pixel side of the drain signal linein an overlapping manner, and the drain-signal-line-side frame portionof the counter electrode of the first pixel and thedrain-signal-line-side frame portion of the counter electrode of thesecond pixel are formed in common on the drain signal line in a stridingmanner.

(8) The present invention is also directed to a liquid crystal displaydevice having a first substrate and a second substrate which arearranged to face each other with liquid crystal sandwiched therebetween,wherein the first substrate forms a plurality of gate signal lines and aplurality of drain signal lines on a liquid-crystal-side surfacethereof, assuming a region surrounded by a pair of neighboring gatesignal lines and a pair of neighboring drain signal lines as a pixelregion of one pixel, the pixel includes a thin film transistor which isturned on in response to a signal from the gate signal line, a pixelelectrode to which a signal from the drain signal line is supplied viathe thin film transistor, and a counter electrode which generates anelectric field for driving the liquid crystal between the pixelelectrode and the counter electrode which are formed on theliquid-crystal-side surface of the first substrate, the counterelectrode is formed of a transparent conductive film having a planarshape which is formed in a state that the transparent conductive film ofthe counter electrode extends over the neighboring pixel striding overat least the drain signal line, the transparent conductive film of thecounter electrode being formed on a first insulation film which isformed on the first substrate so as to cover the drain signal line, thepixel electrode is formed of a transparent conductive film whichincludes a plurality of linear portions arranged parallel to each otherand a frame portion which connects end portions of the linear portionsto each other, the transparent conductive film of the pixel electrodebeing formed in each pixel region on a second insulation film which isformed on the first substrate so as to cover the counter electrode, andthe plurality of linear portions of the pixel electrode being arrangedon the counter electrode in an overlapping manner, and assuming twopixels which are arranged adjacent to each other with the drain signalline formed as a boundary therebetween as a first pixel and a secondpixel respectively, a drain-signal-line-side frame portion of the pixelelectrode of the first pixel is formed on a first-pixel side of thedrain signal line in an overlapping manner, and a drain-signal-line-sideframe portion of the pixel electrode of the second pixel is formed on asecond-pixel side of the drain signal line in an overlapping manner.

Here, the present invention is not limited to the above-mentionedconstitutions and various modifications are conceivable withoutdeparting from the technical concept of the present invention. Further,examples of the constitution of the present invention other than theabove-mentioned constitutions will become apparent due to the wholedescription of this specification and drawings.

According to the liquid crystal display device of the present invention,the liquid crystal display device can realize the increase of thenumerical aperture.

Other advantageous effects obtained by the present invention will becomeapparent due to the description of the whole specification.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of essential parts of a liquid crystaldisplay device according to an embodiment 1 of the present invention;

FIG. 2 is a plan view showing the schematic constitution of the liquidcrystal display device of the present invention;

FIG. 3 is a plan view of a pixel according to the embodiment 1 of theliquid crystal display device of the present invention;

FIG. 4A is a cross-sectional view taken along a line IV(a)-IV(a) in FIG.3, and FIG. 4B is a cross-sectional view taken along a line IV(b)-IV(b)in FIG. 3;

FIG. 5 is a plan view of a pixel according to an embodiment 2 of aliquid crystal display device of the present invention;

FIG. 6 is a cross-sectional view taken along a line VI-VI in FIG. 5; and

FIG. 7A is a cross-sectional view taken along a line VII(a)-VII(a) inFIG. 5, and FIG. 7B is a cross-sectional view taken along a lineVII(b)-VII(b).

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of the present invention are explained in conjunction withdrawings. Here, in the respective drawings and respective embodiments,identical or similar constitutional elements are given the same symbols,and their repeated explanation is omitted.

Embodiment 1 (Whole Constitution)

FIG. 2 is a whole constitutional view showing one embodiment of theliquid crystal display device of the present invention.

In FIG. 2, the liquid crystal display device is configured such that apair of substrates consisting of a substrate SUB1 and a substrate SUB2which is arranged to face each other in an opposed manner and is made ofglass, for example, forms an envelope, and liquid crystal (not shown inthe drawing) is sandwiched between the substrate SUB1 and the substrateSUB2. The liquid crystal is sealed in a space formed between thesubstrate SUB1 and the substrate SUB2 using a sealing member SL whichalso performs a function of fixing the substrate SUB1 and the substrateSUB2, and a region which is surrounded by the sealing member SLconstitutes a display region AR.

An area of the substrate SUB1 is set larger than an area of thesubstrate SUB2 and hence, for example, the substrate SUB1 has regionswhich are exposed from the substrate SUB2 at a left side portion and anupper side portion thereof in the drawing. A plurality of semiconductordevices SCN(V) which is arranged parallel to each other is mounted onthe region of the left side portion of the substrate SUB1, and aplurality of semiconductor devices SCN (He) which is arranged parallelto each other is mounted on a region of an upper side portion of thesubstrate SUB1. The plurality of semiconductor devices SCN (V)constitutes a scanning signal drive circuit and is connected to gatesignal lines GL described later, and the plurality of semiconductordevices SCN (He) constitutes a video signal drive circuit and isconnected to drain signal lines DL described later.

The gate signal lines GL which extend in the x direction and arearranged parallel to each other in the y direction in the drawing andthe drain signal lines DL which extend in the y direction and arearranged parallel to each other in the x direction in the drawing areformed on a liquid-crystal-side surface of the substrate SUB1 within thedisplay region AR.

A rectangular region which is surrounded by the pair of neighboring gatesignal lines GL and the pair of neighboring drain signal lines DLconstitutes a region in which a pixel is formed. Due to suchconstitution, the respective pixels are arranged in a matrix arraywithin the display region AR. Left end portions of the respective gatesignal lines GL extend to the outside of the display region AR aftergetting over the sealing member SL and, thereafter, are connected tooutput terminals of the semiconductor devices SCN(V) arranged in thevicinity of the display region AR, and scanning signals (voltages) aresupplied to the gate signal lines GL by the semiconductor devicesSCN(V). Upper end portions of the respective drain signal lines DLextend to the outside of the display region AR after getting over thesealing member SL and, thereafter, are connected to output terminals ofthe semiconductor devices SCN (He) arranged in the vicinity of thedisplay region AR, and video signals (voltages) are supplied to thedrain signal lines DL by the semiconductor devices SCN (He).

As shown in a circular frame P′ which is an enlarged view of a portionin the drawing which is described by a circular frame P, for example,the pixel includes a thin film transistor TFT which is turned on inresponse to a scanning signal from the gate signal line GL, a pixelelectrode PX to which the video signal from the drain signal line DL issupplied via the thin film transistor TFT in an ON state, and a counterelectrode CT to which a reference signal (voltage) is applied so as togenerate an electric field by making use of a potential differencebetween the pixel electrode PX and the counter electrode CT. The pixelelectrode PX and the counter electrode CT are formed on the samesubstrate SUB1, and an electric field includes an electric fieldcomponent which is parallel to a surface of the substrate SUB1 in aportion thereof. A method which moves (drives) liquid crystal moleculesusing such an electric field is referred to as a lateral-electric field(In Plane Switching) method. Here, to the counter electrode CT, thereference signal is applied through a counter voltage signal line CLwhich is arranged parallel to the gate signal line GL, the countervoltage signal line CL extends after getting over the sealing member SLand is connected to a counter voltage terminal CTM which is formed onthe surface of the substrate SUB1.

In the above-mentioned embodiment, the scanning signal drive circuit Vand the video signal drive circuit He are mounted on the substrate SUB1.However, mounting of these circuits is not limited to theabove-mentioned constitution. That is, semiconductor devices (eachsemiconductor device constituted by mounting a semiconductor chip on aflexible printed circuit board) which are formed by a so-calledtape-carrier method may be arranged in a state that the semiconductordevices extend between the substrate SUB1 and the printed circuit boardnot shown in the drawing.

(Constitution of Pixel)

FIG. 3 is a plan view showing one embodiment of the constitution of thepixel which is formed on the substrate SUB1. Further, FIG. 1 is across-sectional view taken along a line I-I in FIG. 3, FIG. 4A is across-sectional view taken along a line IV(a)-IV(a) in FIG. 3, and FIG.4B is a cross-sectional view taken along a line IV(b)-IV(b) in FIG. 3.Here, FIG. 1 shows the cross section of the pixel including thesubstrate SUB2.

First of all, in FIG. 3, on a liquid-crystal-side surface (frontsurface) of the substrate SUB1, the gate signal lines GL extending inthe x direction in the drawing are arranged parallel to each other inthe y direction. The pixel region is formed of a region which issurrounded by the respective gate signal lines GL and the drain signallines DL described later.

Further, an insulation film GI (see FIG. 1, FIG. 4A and FIG. 4B) isformed on the surface of the substrate SUB1 so as to cover the gatesignal lines GL. The insulation film GI functions as a gate insulationfilm for the thin film transistor TFT in a thin-film-transistor-TFTforming region described later, and a film thickness of the insulationfilm GI is set to a thickness suitable for the gate insulation film.

A non-crystalline semiconductor layer AS made of amorphous silicon, forexample, is formed on a portion of an upper surface of the insulationfilm GI which overlaps with a portion of the gate signal lines GL. Thesemiconductor layer AS constitutes a semiconductor layer of the thinfilm transistor TFT.

Further, the drain signal lines DL which extend in the y direction andare arranged parallel to each other in the x direction in the drawingare formed on the surface of the substrate SUB1. At an intersectionportion between the drain signal line DL and the gate signal line GL,the drain signal line DL extends on the gate signal line GL toward thethin film transistor TFT forming region. The extending portion of thedrain signal line DL extends to and reaches an upper surface of thesemiconductor layer AS thus constituting a drain electrode DT of thethin film transistor TFT.

Further, a source electrode ST which is formed simultaneously with thedrain signal line DL and the drain electrode DT is formed on thesemiconductor layer AS in a state that the source electrode ST faces thedrain electrode DT in an opposed manner. The source electrode ST extendstoward the pixel region from a position above the semiconductor layerAS, and an extending portion of the source electrode ST includes a padportion PD. The pad portion PD forms a portion which is electricallyconnected with the pixel electrode PX described later and has an arealarger than an area of the portion of the source electrode ST arrangedabove the semiconductor layer AS.

Due to such constitution, the thin film transistor TFT is formed of anMIS (Metal Insulator Semiconductor)-type transistor having the so-calledinversely-staggered structure in which a portion of the gate signal lineGL constitutes the gate electrode.

On the front surface of the substrate SUB1, a protective film PAS formedof a stacked body which is obtained by sequentially stacking aninorganic insulation film PASi and an organic insulation film PASo, forexample, is formed in a state that the protective film PAS also coversthe thin film transistor TFT. By forming an upper layer of theprotective film PAS using an organic insulation film PASo, a surface ofthe protective film PAS can be leveled.

Further, on an upper surface of the protective film PAS, the pixelelectrode PX is formed using a transparent conductive film such as anITO film (Indium Tin Oxide) film, for example. The pixel electrode PX isconstituted as a surface electrode having a planar shape which is formedso as to cover the substantially whole area of the pixel region forevery pixel. In this embodiment, an upper side of the pixel electrode PXin the drawing is formed to overlap with a pixel side of the gate signalline GL which is arranged on an upper side of the pixel in the drawing(indicated by symbol ovr in the drawing), and a lower side of the pixelelectrode PX in the drawing is formed to overlap with a pixel side ofthe gate signal line GL which is arranged on a lower side of the pixelin the drawing (indicated by symbol ovr in the drawing). Due to suchconstitution, as shown in FIG. 1, out of respective sides of the gatesignal line GL which extend parallel to each other in the runningdirection of the gate signal line GL, the pixel electrode PX of thepixel overlaps with one side of the gate signal line GL (indicated bysymbol ovr in the drawing), and a pixel electrode PX of another pixelwhich is arranged adjacent to the above-mentioned pixel with the gatesignal line GL formed as a boundary therebetween overlaps with anotherside of the gate signal line GL (indicated by symbol ovr in thedrawing). Further, returning to FIG. 3, a left side of the pixelelectrode PX in the drawing is formed to overlap with apixel-electrode-PX side of the drain signal line DL which is arranged ona left side of the pixel electrode PX in the drawing (indicated bysymbol ovr′ in the drawing), and a right side of the pixel electrode PXin the drawing is formed to overlap with a pixel side of the drainsignal line DL which is arranged on a right side of the pixel in thedrawing (indicated by symbol ovr′ in the drawing). Due to suchconstitution, as shown in FIG. 4B, out of respective sides of the drainsignal line DL which extend parallel to each other in the runningdirection of the drain signal line DL, the pixel electrode PX of thepixel overlaps with one side of the drain signal line (indicated bysymbol ovr′ in the drawing), and a pixel electrode PX of another pixelwhich is arranged adjacent to the above-mentioned pixel with the drainsignal line DL formed as a boundary therebetween overlaps with anotherside of the drain signal line DL (indicated by symbol ovr′ in thedrawing).

Here, the pixel electrode PX is electrically connected to the padportion PD via a through hole TH (see FIG. 4A) which is formed in theprotective film PAS so as to expose the pad portion PD of the sourceelectrode ST of the thin film transistor TFT.

On the front surface of the substrate SUB1, an insulation film IN (seeFIG. 1, FIG. 4A and FIG. 4B) which is formed of an inorganic insulationfilm is formed so as to cover the pixel electrodes PX. The insulationfilm IN functions as a dielectric film for forming a holding capacitancebetween the pixel electrode PX and the counter electrode CT describedlater which is formed on an upper surface of the insulation film IN.

The counter electrode CT is formed of a transparent conductive film suchas an ITO (Indium Tin Oxide) film, for example. Further, the counterelectrode CT is formed of a plurality of linear electrodes which isarranged parallel to each other in a state that these linear electrodesoverlap with the pixel electrode PX. That is, the counter electrode CTis formed by forming a plurality of slits SLT which are arrangedparallel to each other in the transparent conductive film which extendsto and reaches the neighboring pixels from the pixel after getting overthe gate signal lines GL and the drain signal lines DL for every pixelregion. Here, the counter electrode CT provided for every pixel regionis configured such that the plurality of linear electrodes which isarranged parallel to each other is integrally connected to frameportions CT(FR), CT (FR′) which are connected with each other around thelinear electrodes.

Further, returning to FIG. 3, the frame portion CT (FR) of the counterelectrode CT on an upper side of the drawing is formed in common with aframe portion CT (FR) of the counter electrode CT of another pixel whichis arranged adjacent to the pixel on a lower side of the drawing withthe upper gate signal line GL formed as a boundary therebetween, and thecommon frame portion CT(FR) overlaps at least with the gate signal lineGL. Further, the frame portion CT(FR) of the counter electrode CT on alower side of the drawing is formed in common with a frame portion CT(FR) of the counter electrode CT of another pixel which is arrangedadjacent to the pixel on an upper side of the drawing with the gatesignal line GL on a lower side of the drawing formed as a boundarytherebetween, and the common frame portion CT(FR) overlaps at least withthe gate signal line GL. Due to such constitution, as shown in FIG. 1,the frame portion CT(FR) of the counter electrode CT is arranged suchthat the frame portion CT(FR) covers a gap portion between the pixelelectrodes PX of the respective pixels which are arranged adjacent toeach other with the gate signal line GL formed as a boundarytherebetween above the gate signal line GL, and includes overlappingportions ovr which overlap with the respective pixel electrodes PX.

Accordingly, as can be clearly understood also from FIG. 1, the gatesignal line GL and an area surrounding the gate signal line GL arecompletely covered with the pixel electrodes PX and the counterelectrodes CT. Due to such constitution, all of lines of electric forcewhich are generated from the gate signal line GL which constitutes astart point of lines of electric force are terminated at the pixelelectrodes PX or the counter electrodes CT, and there exists nopossibility that the lines of electric force reach aliquid-crystal-LC-side layer. Accordingly, the liquid crystal arrangedin the vicinity of the gate signal line GL is not influenced at all bythe lines of electric force generated from the gate signal line GL andhence, in each pixel, molecules of the liquid crystal LC can be normallydriven in a range which also covers a region close to the gate signalline GL. Further, lines of electric force generated from the pixelelectrode PX of the neighboring pixel can also be terminated at thecounter electrode CT which includes the overlapping portion ovr betweenthe pixel electrode PX and the counter electrode CT and hence, it isalso possible to prevent the liquid crystal molecules from beinginfluenced by the lines of electric force generated from the pixelelectrode of the neighboring pixel. Accordingly, a width w of a blackmatrix (light blocking film) BM which is formed on the substrate SUB2side so as to overlap with the gate signal lines GL can be decreasedcompared to a width of the conventional black matrix BM thus increasinga numerical aperture of the pixel. In this case, according to thisembodiment, the overlapping portion ovr between the pixel electrode PXand the counter electrode CT is configured to be positioned above thegate signal line GL and hence, the width w of the black matrix BM can beset smaller than a width W of the gate signal line GL. Here, in FIG. 1,color filters FIL are formed in the respective pixel regions of thepixels which are arranged adjacent to each other with the black matrixBM formed as a boundary therebetween on a liquid-crystal-side surface ofthe substrate SUB2.

Further, by forming the overlapping portion ovr between the pixelelectrode PX and the counter electrode CT above the gate signal line GL,end portions of the slits SLT of the counter electrode CT can be formedclose to the gate signal line GL thus increasing a region of the counterelectrode CT which functions as an electrode. Also from this viewpoint,it is possible to increase the numerical aperture of the pixel.

Further, returning to FIG. 3, the frame portion of the counter electrodeCT on a left side of the drawing is formed in common with a frameportion of the counter electrode CT of another pixel which is arrangedadjacent to the pixel on a right side of the drawing with the drainsignal line DL formed on a left side of the drawing as a boundarytherebetween, and the common frame portion CT(FR′) overlaps at leastwith the drain signal line DL. Further, the frame portion CT(FR′) of thecounter electrode CT on a right side of the drawing is formed in commonwith a frame portion CT (FR′) of the counter electrode CT of anotherpixel which is arranged adjacent to the pixel on a left side of thedrawing with the drain signal line DL formed on a right side of thedrawing as a boundary therebetween, and the common frame portion CT(FR′)is configured to overlap at least with the drain signal line DL. Due tosuch constitution, as shown in FIG. 4B, the frame portion CT (FR′) ofthe counter electrode CT is arranged such that the frame portion CT(FR′) covers a gap portion between the pixel electrodes PX of therespective pixels which are arranged adjacent to each other with thedrain signal line DL formed as the boundary therebetween above the drainsignal line DL, and includes the overlapping portions ovr′ which overlapwith the respective pixel electrodes PX.

Accordingly, as can be clearly understood also from FIG. 4B, the drainsignal line DL and an area surrounding the drain signal line DL arecompletely covered with the pixel electrodes PX and the counterelectrodes CT. Due to such constitution, all of lines of electric forcewhich is generated from the drain signal line DL which constitutes astart point of lines of electric force are terminated at the pixelelectrodes PX or the counter electrodes CT, and there exists nopossibility that the lines of electric force reach aliquid-crystal-LC-side layer. Further, lines of electric force from thepixel electrode PX of the neighboring pixel can be also terminated atthe counter electrode CT which includes an overlapping portion ovr′between the pixel electrode PX and the counter electrode CT and hence,it is also possible to prevent the liquid crystal molecules from beinginfluenced by the lines of electric force from the pixel electrode ofthe neighboring pixel. Accordingly, the liquid crystal arranged in thevicinity of the drain signal line DL is not influenced by the lines ofelectric force generated from the drain signal line DL and hence, ineach pixel, the molecules of the liquid crystal LC can be normallydriven in a range which also covers a region close to the drain signallines DL. Accordingly, although not shown in FIG. 4B, when the blackmatrix (light blocking film) BM is formed on the substrate SUB2 side ina state that the black matrix BM overlaps with the drain signal linesDL, a width of the black matrix BM can be decreased compared to a widthof a conventional black matrix thus increasing the numerical aperture ofthe pixel. In this case, the overlapping portion between the pixelelectrode PX and the counter electrode CT is positioned above the drainsignal line DL and hence, the width of the black matrix BM can be setsmaller than a width of the drain signal line DL.

In the pixel shown in FIG. 3, the semiconductor layer of the thin filmtransistor TFT is made of an amorphous material. However, the pixel mayinclude a thin film transistor TFT which is formed of a semiconductorlayer which is usually referred to as polysilicon. The same goes forembodiments described later.

Further, in the pixel shown in FIG. 3, the black matrix BM is formed onthe substrate SUB2 side so as to overlap with the drain signal lines DL.However, the black matrix BM may not always be made to overlap with thedrain signal lines DL. The same goes for the embodiments describedlater.

Further, in the pixel shown in FIG. 3, in the same manner as the gatesignal lines GL, also in the drain signal line DL side, the respectivepixel electrodes PX of the pixels which are arranged adjacent to eachother with the drain signal line DL formed as a boundary therebetweenoverlap with the drain signal line DL, and the drain signal line DL iscovered with the counter electrode CT. However, it may be possible thatsuch constitution is adopted on the gate signal line GL side but is notadopted on the drain signal line DL side. This is because the width ofthe drain signal line DL is extremely narrow compared to the width ofthe gate signal line GL. The same goes for the embodiments describedlater. As an opposite case, it may be possible that the constitutionexplained in conjunction with this embodiment is adopted on the drainsignal line DL side but is not adopted on the gate signal line GL side.

With respect to the constitution of the pixel explained in conjunctionwith the embodiment 1, to simplify the explanation of the constitution,an alignment film which constitutes an uppermost layer on respectiveliquid-crystal sides of the substrate SUB1 and the substrate SUB2 isomitted from the drawing. The same goes for the embodiments describedhereinafter.

Embodiment 2

FIG. 5 is a plan view for explaining one example of the liquid crystaldisplay device of an embodiment 2 of the present invention andcorresponds to FIG. 3. Further, FIG. 6 is a cross-sectional view takenalong a line VI-VI in FIG. 5, FIG. 7A is a cross-sectional view takenalong a line VII(a)-VII(a) in FIG. 5, and FIG. 7B is a cross-sectionalview taken along a line VII(b)-VII(b) in FIG. 5. Here, FIG. 6 shows across section of the liquid crystal display device including a substrateSUB2.

The constitution which makes this embodiment 2 largely different fromthe embodiment 1 shown in FIG. 3 lies in that the arrangementrelationship of the layered structure between the pixel electrode PX andthe counter electrode CT of this embodiment 2 is opposite to thecorresponding arrangement relationship of the embodiment 1. That is, inthis embodiment 2, a counter electrode CT is formed on an upper surfaceof a protective film PAS which is formed so as to cover thin filmtransistors TFT and, further, pixel electrodes PX are formed on aninsulation film IN which is formed so as to cover the counter electrodeCT. In this case, for generating an electric field on a liquid crystalLC side, the counter electrode CT which is formed as a lower layer isformed of a surface transparent conductive film having a planar shape,and the pixel electrode PX which is formed as an upper layer is formedof a transparent conductive film having a plurality of linear portionswhich is arranged parallel to each other.

To be more specific, the counter electrode CT is formed on the firstsubstrate such that the counter electrode CT reaches neighboring otherpixels striding over the gate signal lines GL and the drain signal linesDL which define the pixel. Due to such constitution, in each pixelregion, the counter electrode CT is formed on the whole region of thedisplay region AR (see FIG. 2) while avoiding regions where throughholes TH described later which are provided for establishing theelectrical connection between the thin film transistors TFT and thepixel electrodes PX are formed (a profile of the counter electrode CTbeing indicated by symbol CT (OL) in FIG. 5).

Further, the pixel electrode PX is independently formed for every pixelregion, and includes frame portions PX(FR), PX(FR′) which connectperipheral end portions of a plurality of linear portions arrangedparallel to each other. The frame portions PX (FR), PX (FR′) areprovided for electrically connecting electrodes which are respectivelyformed of the linear portions to each other.

As shown in FIG. 6, in another neighboring pixel which is arrangedadjacent to the pixel with the gate signal line GL formed as a boundarytherebetween, the gate-signal-line-GL-side frame portion PX(FR) of thepixel electrode PX of the pixel is formed on the substrate SUB1 so as tooverlap with the pixel side of the gate signal line GL (indicated bysymbol ovr in the drawing), and the gate-signal-line-GL-side frameportion PX (FR) of the pixel electrode PX of another pixel is formed onthe substrate SUB1 so as to overlap with the another-pixel-side of thegate signal line GL (indicated by symbol ovr in the drawing).

Accordingly, a gap portion formed between the pixel electrode PX of onepixel and the pixel electrode PX of another pixel which is arrangedadjacent to one pixel PX with the gate signal line GL formed as aboundary therebetween can be made small and, at the same time, the gapportion can be positioned above the gate signal line GL. This eventuallynarrows a range of a region of an electric field which is generatedbetween the respective pixel electrodes PX of the neighboring pixelswith the gate signal line GL sandwiched therebetween (that is, anelectric field generated between the pixel electrodes PX of theneighboring pixels). Further, this gap portion can be shielded fromlight by the gate signal line GL. Due to such constitution, as shown inFIG. 6, it is sufficient for the black matrix (light blocking film) BMwhich is arranged on the substrate SUB2 in an overlapping manner withthe gate signal line GL to cover only the gap portion formed between thepixel electrodes PX which are arranged adjacent to each other, and awidth w of the black matrix BM may be set smaller than at least a widthW of the gate signal line GL.

Here, the pixel electrode PX is connected to a source electrode ST (padportion PD) of the thin film transistor TFT via a through hole TH formedin an insulation film IN and a protective film PAS. In this case, asdescribed previously, the counter electrode CT is formed while avoidingthe regions where the through holes TH are formed.

Further, as shown in FIG. 7B, in another pixel which is arrangedadjacent to the pixel with the drain signal line DL formed as a boundarytherebetween, the drain-signal-line-DL-side frame portion PX (FR′) ofthe pixel electrode PX of the pixel overlaps with the pixel side of thedrain signal line DL (indicated by symbol ovr′), and thedrain-signal-line-DL-side frame portion PX (FR′) of the pixel electrodePX of another pixel overlaps with another pixel side of the drain signalline DL (indicated by symbol ovr′).

Accordingly, a gap portion formed between the pixel electrode PX of onepixel and the pixel electrode PX of another pixel which is arrangedadjacent to one pixel PX with the drain signal line DL formed as aboundary therebetween can be made small and, at the same time, the gapportion can be positioned above the drain signal line DL. Thiseventually narrows a range of a region of an electric field which isgenerated between the respective pixel electrodes PX of the neighboringpixels with the drain signal line DL sandwiched therebetween (that is,an electric field generated between the pixel electrodes PX of theneighboring pixels). Further, this gap portion can be shielded fromlight by the drain signal line DL. Due to such constitution, althoughomitted from FIG. 7B, provided that the black matrix (light blockingfilm) BM is arranged on the substrate SUB2 in an overlapping manner withthe drain signal line DL, it is sufficient for the black matrix BM tocover only the gap portion formed between the pixel electrodes PX, and awidth of the black matrix BM may be set smaller than at least a width ofthe drain signal line DL.

Also in this embodiment, the overlapping portion ovr is formed on thegate signal line GL side and the overlapping portion ovr′ is not formedon the drain signal line DL side. As an opposite case, the overlappingportion ovr is not formed on the gate signal line GL side and theoverlapping portion ovr′ is formed on the drain signal line DL side.

Although the present invention has been explained in conjunction withthe embodiments, the constitutions explained heretofore in conjunctionwith respective embodiments are merely examples, and the presentinvention can be suitably modified without departing from a technicalconcept of the present invention. Further, the constitutions explainedin conjunction with the respective embodiments may be used incombination unless these constitutions contradict each other.

1. A liquid crystal display device having a first substrate and a secondsubstrate which are arranged to face each other with liquid crystalsandwiched therebetween, wherein the first substrate forms a pluralityof gate signal lines and a plurality of drain signal lines on aliquid-crystal-side surface thereof, assuming a region surrounded by apair of neighboring gate signal lines and a pair of neighboring drainsignal lines as a pixel region of one pixel, the pixel includes a thinfilm transistor which is turned on in response to a signal from the gatesignal line, a pixel electrode to which a signal from the drain signalline is supplied via the thin film transistor, and a counter electrodewhich generates an electric field for driving the liquid crystal betweenthe pixel electrode and the counter electrode which are formed on theliquid-crystal-side surface of the first substrate, the pixel electrodeis formed of a transparent conductive film having a planar shape whichis formed in each pixel region on a first insulation film which isformed on the first substrate so as to cover the gate signal line, thecounter electrode is formed of a transparent conductive film whichincludes a plurality of linear portions arranged parallel to each otherand a frame portion which connects end portions of the linear portionsto each other, the transparent conductive film of the counter electrodebeing formed on a second insulation film which is formed on the firstsubstrate so as to cover the pixel electrode, and the plurality oflinear portions of the counter electrode being arranged on the pixelelectrode in an overlapping manner, and a gate-signal-line side of thepixel electrode is formed on the pixel side of the gate signal line inan overlapping manner, and a gate-signal-line-side frame portion of thecounter electrode of the first pixel and a gate-signal-line-side frameportion of the counter electrode of the second pixel are formed incommon on the gate signal line in a striding manner.
 2. A liquid crystaldisplay device according to claim 1, wherein the liquid crystal displaydevice forms alight blocking film which is arranged so as to overlapwith the gate signal line on the second substrate, and a width of thelight blocking film is set smaller than a width of the gate signal line.3. A liquid crystal display device according to claim 1, whereinassuming two pixels which are arranged adjacent to each other with thedrain signal line formed as a boundary therebetween as one pixel andanother pixel respectively, a drain-signal-line side of the pixelelectrode of said one pixel is formed on one-pixel side of the drainsignal line in an overlapping manner, and a drain-signal-line side ofthe pixel electrode of said another pixel is formed on another-pixelside of the drain signal line in an overlapping manner, and adrain-signal-line-side frame portion of the counter electrode of saidone pixel and a drain-signal-line-side frame portion of the counterelectrode of said another pixel are formed in common on the drain signalline in a striding manner.
 4. A liquid crystal display device having afirst substrate and a second substrate which are arranged to face eachother with liquid crystal sandwiched therebetween, wherein the firstsubstrate forms a plurality of gate signal lines and a plurality ofdrain signal lines on a liquid-crystal-side surface thereof, assuming aregion surrounded by a pair of neighboring gate signal lines and a pairof neighboring drain signal lines as a pixel region of one pixel, thepixel includes a thin film transistor which is turned on in response toa signal from the gate signal line, a pixel electrode to which a signalfrom the drain signal line is supplied via the thin film transistor, anda counter electrode which generates an electric field for driving theliquid crystal between the pixel electrode and the counter electrodewhich are formed on the liquid-crystal-side surface of the firstsubstrate, the counter electrode is formed of a transparent conductivefilm having a planar shape which is formed in a state that thetransparent conductive film of the counter electrode extends over theneighboring pixel striding over at least the gate signal line, thetransparent conductive film of the counter electrode being formed on afirst insulation film which is formed on the first substrate so as tocover the gate signal line, the pixel electrode is formed of atransparent conductive film which includes a plurality of linearportions arranged parallel to each other and a frame portion whichconnects end portions of the linear portions to each other, thetransparent conductive film of the pixel electrode being formed in eachpixel region on a second insulation film which is formed on the firstsubstrate so as to cover the counter electrode, and the plurality oflinear portions of the pixel electrode being arranged on the counterelectrode in an overlapping manner, and a gate-signal-line-side frameportion of the pixel electrode is formed on the pixel side of the gatesignal line in an overlapping manner.
 5. A liquid crystal display deviceaccording to claim 4, wherein the liquid crystal display device formsalight blocking film which is arranged so as to overlap with the gatesignal line on the second substrate, and a width of the light blockingfilm is set smaller than a width of the gate signal line.
 6. A liquidcrystal display device according to claim 4, wherein assuming two pixelswhich are arranged adjacent to each other with the drain signal lineformed as a boundary therebetween as one pixel and another pixelrespectively, a drain-signal-line-side frame portion of the pixelelectrode of said one pixel is formed on one-pixel side of the drainsignal line in an overlapping manner, and a drain-signal-line side ofthe pixel electrode of said another pixel is formed on another-pixelside of the drain signal line in an overlapping manner.
 7. A liquidcrystal display device having a first substrate and a second substratewhich are arranged to face each other with liquid crystal sandwichedtherebetween, wherein the first substrate forms a plurality of gatesignal lines and a plurality of drain signal lines on aliquid-crystal-side surface thereof, assuming a region surrounded by apair of neighboring gate signal lines and a pair of neighboring drainsignal lines as a pixel region of one pixel, the pixel includes a thinfilm transistor which is turned on in response to a signal from the gatesignal line, a pixel electrode to which a signal from the drain signalline is supplied via the thin film transistor, and a counter electrodewhich generates an electric field for driving the liquid crystal betweenthe pixel electrode and the counter electrode which are formed on theliquid-crystal-side surface of the first substrate, the pixel electrodeis formed of a transparent conductive film having a planar shape whichis formed in each pixel region on a first insulation film which isformed on the first substrate so as to cover the drain signal line, thecounter electrode is formed of a transparent conductive film whichincludes a plurality of linear portions arranged parallel to each otherand a frame portion which connects end portions of the linear portionsto each other, the transparent conductive film of the counter electrodebeing formed on a second insulation film which is formed on the firstsubstrate so as to cover the pixel electrode, and the plurality oflinear portions of the counter electrode being arranged on the pixelelectrode in an overlapping manner, and a drain-signal-line side of thepixel electrode is formed on the pixel side of the drain signal line inan overlapping manner, and a drain-signal-line-side frame portion of thecounter electrode of the first pixel and a drain-signal-line-side frameportion of the counter electrode of the second pixel are formed incommon on the drain signal line in a striding manner.
 8. A liquidcrystal display device having a first substrate and a second substratewhich are arranged to face each other with liquid crystal sandwichedtherebetween, wherein the first substrate forms a plurality of gatesignal lines and a plurality of drain signal lines on aliquid-crystal-side surface thereof, assuming a region surrounded by apair of neighboring gate signal lines and a pair of neighboring drainsignal lines as a pixel region of one pixel, the pixel includes a thinfilm transistor which is turned on in response to a signal from the gatesignal line, a pixel electrode to which a signal from the drain signalline is supplied via the thin film transistor, and a counter electrodewhich generates an electric field for driving the liquid crystal betweenthe pixel electrode and the counter electrode which are formed on theliquid-crystal-side surface of the first substrate, the counterelectrode is formed of a transparent conductive film having a planarshape which is formed in a state that the transparent conductive film ofthe counter electrode extends over the neighboring pixel striding overat least the drain signal line, the transparent conductive film of thecounter electrode being formed on a first insulation film which isformed on the first substrate so as to cover the drain signal line, thepixel electrode is formed of a transparent conductive film whichincludes a plurality of linear portions arranged parallel to each otherand a frame portion which connects end portions of the linear portionsto each other, the transparent conductive film of the pixel electrodebeing formed in each pixel region on a second insulation film which isformed on the first substrate so as to cover the counter electrode, andthe plurality of linear portions of the pixel electrode being arrangedon the counter electrode in an overlapping manner, and adrain-signal-line-side frame portion of the pixel electrode is formed onthe pixel side of the drain signal line in an overlapping manner.